The human body is designed to maintain a temperature of 37 degrees Celsius, or 98.6 degrees Fahrenheit. Our skin harbors temperature receptors that notice when the temperature outside the body fluctuates. When this occurs, those receptors react like a biological Paul Revere, and shoot a warning signal to the processing center of the brain, the hypothalamus, indicating that the British are coming. The hypothalamus responds by sending in the troops, our muscles and sweat glands, which then try to hold the fort, or the core body temperature, at a constant level. But sometimes, in extreme weather, the troops need some help.

In order to survive in acute heat or cold, you’ll need to help your body out with a few preparations and some temperature sustaining hacks.

Stay Warm

When stranded in the wilderness or in a chilly tundra, your number one concern is going to be avoiding hypothermia. Hypothermia, a life threatening condition, ensues when your body cannot produce heat at a rate that is faster than the rate the body is losing heat, which results in a very low, potentially fatal, body temperature. The nervous system and vital organs are unable to function properly under hypothermia conditions, and if you do not receive help fast, your respiratory system and heart could fail. So when going out into the cold, it is best to go out prepared for the worst. Here are some tips to keep you warm:

Layers: Layers are your first defense against extreme cold. Optimal layering will consist of three parts: base layer, middle layer, and outer layer. The base layer should be fitted to the body, but not too tightly. Avoid cotton, since it traps moisture; instead, a base layer of merino wool is recommended. The middle layer should be made of a breathable material, like flannel shirts, and should preferably have a collar or hood. Lastly, the outer layer should be made from a waterproof and wind resistant material that covers your body past the waist. Do not forget the hat and gloves.

Hand warmers: In addition to gloves, hand warmers are a small hack that might make all the difference, and best of all, you can make these yourself. To do so, fill a large, quart-size zip-lock bag, about a quarter full, with ice-melt pellets. These can be found at any hardware store. Fill up a smaller, sandwich-size zip-lock bag about halfway with water, seal it, then place it in the larger bag and extract any excess air before sealing it. When you are ready for a shot of heat, squeeze the sandwich bag until it bursts. The water will mix with the pellets and create a heat reaction within the bag that can last up to an hour. One in each pocket should do the trick.

Keep Cool

The human body is just as sensitive to extreme heat as it is to extreme cold. If you are in an arid, hot desert or region for an extended length of time, you will run the risk of experiencing hyperthermia, hypothermia’s nasty cousin. A condition which occurs when the heat gain of the body surpasses the body’s ability expunge heat, hyperthermia can also be fatal. Under normal circumstances, when in a hot environment or when exerting yourself physically, the sweat glands jump into motion and dispel the extra heat through your pores, but when the duration of the physical stress or exposure to excessive temperature goes on for too long, the body can no longer regulate temperature, resulting in heat exhaustion or heat stroke. If the body’s temperature hits 41 degrees Celsius, 106 degrees Fahrenheit, you could very likely die. Here are some tips to keep you cool:

Hydrate: Drink water throughout the day and keep extra water on hand. Though this may seem like common sense, it is easy to underestimate the amount of water required to keep the body hydrated. Though it depends on the individual, on average, men need about three liters of water a day and women require 2.2 liters.

Wear light clothing: Clothing that is light both in color and weight is a must in a hot, dry environment. The less tight and constrictive, the better, and select fabrics made from loosely weaved materials so that the air can reach your skin.

Avoid caffeine: Caffeine and alcohol can speed up dehydration. Stick with good, old-fashioned water, or if you have already consumed caffeine or alcohol before trekking out into the heat, double up on the amount of water you take with you.

The human body is a miraculous machine, but if you plan to push the limits of its temperature gauge, it’s best to plan ahead and offer it some assistance. With a preps and hacks, you’ll stay safe and comfortable.